Sampling device for continuous supply of gas



Wm :1? M. T. MAMA-T SAMPLING DEVICE FOR CONTINUOUS SUPPLY OF (ms Filed Feb. 3.2, 1954 2 Sheets Shee't 1 Fig. I

IN MENTOR MN L mm HEN NAME KIM. :3 M p E'FQ KM IK E'; SAMPLING DEVICE FOR CONTINUOUS SUPPLY OF GAS Filed Feb. 12, 1954 2 fil'lraua'ks shee't I2 SAll/ilPLllNG DEVECE FOR CONTINUUUS SUPPLY OF GAS Karl Torsten Kalle, Same, Sweden Application February 12, 1954, Serial No. 409,994

4 (Claims. (Cl. 73-4215) The invention refers to a sampling device for continu' ous supply of a substantially constant amount of gas per unit of time and relates especially to a device for supplying gas to an analyser, such as a gas absorption apparatus, for instance.

When sucking small amounts of gas through narrow jets, for instance for supplying a desired amount of gas per unit of time to an absorption apparatus, for instance of the type described in my pending U. S. application 311,011, traces of impurities are often deposited in the inlet opening, thus decreasing the cross section area of the passage. Even when the gas is purified, impurities may afterwards be precipitated, for instance by sublimation of sulphur in combustion gases. Another drawback is that changes of the area of the inlet opening due to varia tions in the temperature of the gas or the surrounding atmosphere do not correspond to the changes in the volume of the gas, so that also hereby small deviations arise as to the amount of gas supplied.

The sampling device according to the invention has for its object to eliminate these inconveniences. The device comprises two members having surfaces contacting each other. One of the members is arranged to be rotated, while the other is held against rotation. Channels for the gas to be sampled are provided through both members and have orifices in said contacting surfaces. Owing to the rotation of one of the members the flow of gas through the channels becomes intermittent, in that the channels communicate only during a small part of each revolution. Thus, it is possible, while maintaining a desired slight flow of gas, to give the channels such a large cross section that no risk for clogging arises. Moreover, at least one of the elements is movable to cause the channels to communicate more or less during the rotation, and means responsive to variations of temperature are arranged to displace one of the members in relation to the other to compensate variations of the volume of the gas by changing the passage between the channels. In a preferred embodiment the two members consist of cylindrical elements, one journalled in the other.

The device will be more closely described below with reference to the accompanying drawings which show two different embodiments. Figs. 1 and 2 show one embodiment of the device in vertical section and seen from above, respectively, and Pig. 3 shows another and possibly preferred embodiment.

The device according to Fig. 1 comprises a sleeve 3, one end of which is put onto the end of a shaft 4 of an electric motor 5 and fixed to this shaft by means of a pin 6. The sleeve 3 is closely surrounded by an outer sleeve '7 carried by a device which will be described below. Preferably the sleeves are made of a material delivered under the trade name Carbate, and consisting of a mixture of graphite and synthetic resins. This material is very durable, self-lubricating and resistant to chemicals. Moreover, it is known to have excellent heat conductive properties. A channel 8 passes radially through the wall of the inner sleeve 3 from its central hole 9, and

hired States Patent 0 "ice a corresponding channel 10 passes radially through the wall of the outer sleeve 7. A screwed-in socket 11 con nects said channel 10 to a flexible hose 12 of rubber or the like.

Two bimetallic plates or strips 13 are fixed diametrically to the lower end of the outer sleeve 7 and project radially outwards to have their free outer ends supported by an edge-shaped upper end of a horizontal ring 14. Said bimetallic strips are of the type consisting of joint sheets of two metals or alloys having different coetficients of expansion so that the strips will be bent in dependence on their temperature. Such a combination of metals may be lnvar and iron, for instance. The supporting ring 14 is threaded at its inside and screwed on to a ring 15 threaded at its outside and fixed to the motor casing around the shaft 4. The fixed inner ring 15 is provided with two upright forks 16 each grasping one of the two bimetal plates 13, whereby the sleeve 7 is locked against rotation, at the same time as it is free to be moved in axial direction.

A conduit 17 leading from a source of gas over a pump (not shown) has an end portion bent vertically downwards and introduced in the central hole 9 of the sleeve 3 to keep this hole filled with the gas in question. Thus, only some portion of the gas coming from the conduit 17' will be passed through the channels 8, 1i) and the conduit 12, while the rest may escape freely. This device has for its object to make possible a great speed of flow through the conduit 17, although it has a relatively large cross section area to prevent obstructing by impurities in the gas. If the sampling device according to the invention is to be used for continuous supply of small amounts of gas to a gas analyser, it is of importance that the speed of flow is great so that variations occurring in the source of gas can be quickly observed.

The amount of gas flowing through the sampling device can be adjusted by turning the ring 14 so that the sleeve 7 is elevated or lowered, the channels 8, 10 being brought more or less in front of each other. Preferably the channels should have rectangular cross sections, so that the change of the cross section area of the passage will be in proportion to the turning angle of the ring: 14. To facilitate the adjustment, the ring 14 may be knurled externally (at 13) and provided with an index pointing at a scale on the outside of the inner ring 15. Minor changes in the speed of rotation of the motor have no influence upon the amount of gas passing.

The two bimetallic plates 13 carrying the sleeve 7 are arranged to have their outer ends bent downwards to raise the sleeve 7 when the temperature is increased. In the position shown in Fig. 1, the channel 10 is: at a somewhat lower level than the channel 8. Thus, the result is that the common cross section area of the two channels will be increased at increasing temperature. By choosing a suitable combination of metals or alloys in the plates 13 and by dimensioning the diameter of the supporting ring 14 it is possible to get the cross section area of the gas passage changed exactly to correspond and compensate such changes of the volume of the gas passing, which are caused by varying temperatures. Thus, the passage will always transmit a constant weight of gas regardless of the temperature.

In Fig. 3 the device also comprises an inner rotary member 19 and a surrounding, fixed sleeve 2d. The latter is supported by a tubular member 21 mounted on the motor casing 22 around the motor shaft 23. The lower portion of the tube 21 is threaded at its outside to receive an adjusting ring 24 similar to the ring 14 in Fig. 1. The upper portion of the tube has two diametrically opposed, axial slots 25. Two bimetallic strips 26 are fixed diametrically to the underside of a horizontal disk 27 arranged below the sleeve 20. Said strips project through 3 the guide slots 25 to rest on the ring 24 with their outer ends and thereby to support the disk 27.

The inner, rotary member 19 is rotatably supported by the disk 27 and journalled in the sleeve 20. It has two axial borings 28 and 29, one from each end. A plug or disk 30 having a central, quadrangular openingis inserted in the bottom end of the member 19. A square shaft 31 is fixed to the end of the motor shaft 23 and is 'slidably inserted through the quadrangular opening in the disk 30. Thus, the member 19 is caused to' rotate by the shaft 31, when the motor operates, but is free to be displaced in axial direction by the bimetallic strips 26. Preferabiy both members 19 and 20 as well as the disk 27 are made from Carbate.

The sleeve 20 has an inlet 32' which is to be connected to asource of gas over a pump. Said inlet ends into an annular space 33 surrounding a portion of the member 19. A number of radial channels 34 through the Wall of the member 19 connect the space 33 with the boring 28. Anotherradial channel 35 through the member 159 is arranged to cooperate with a channel 36 through the sleeve 20 and this latter channel 36 has an outlet stud 37 which is to be connected to a gas analyzer or similar device through which adesired amount of gas is sucked. Finally, the sleeve 20 has a cap 38 enclosing the upper end of the member 19. This cap has an outlet opening 39 for gas.

Thus, also in this embodiment a surplus of gas is pumped to the sampling device for the same reason as indicated above. Of course, the boring 28 is effectively filled with gas so that no air can enter the channel 35, but, moreover, the room outside the member 19, i. e. inside the cap 38, will be filled with gas which means that no air can penetrate'in a possible lo'os'e fit between the sleeve 20 and the member 19.

In Fig. 3 the bimetallic strips 26 are shown straight and the channel 35 is at a somewhat higher level than the channel 36 so that the two channels together form a restricted passage. In this case the strips 26 are mounted to be bent downwards, i. e. to lower the disk 27, when the temperature is raised, so that the passage between the channels is widened.

The device described may be varied in different ways Within the scope of the invention. Thus it is possible to let the outer member rotate, while the inner one is locked against rotation, and one or both may be provided with several channels. Further, the two members may be shaped as parallel disks having surfaces contacting each other, in that one of the disks is rotatable, and

one of them is supported by bimetal plates to be displaced in dependence on the temperature.

What I claim is:

1. A sampling device for continuous supply of a constant amount of gas per unit of time, comprising two members having surfaces contacting ec ah other, means for rotating one of said members in relation to the other, both members being provided with channels thereth'rough for gas to be sampled, said channels having orifices in said contacting surfaces to communicate periodically when the rotatable member is rotated, and means including at least one bimetallic plate to support one of the members,

4 said plate being bent in dependence on its temperature to displace the supported member in relation to the other member to compensate variations of the volume of the gas by changing the passage area between the channels.

2. A sampling device for continuous supply of a constant amount of gas per unit of time, comprising a cylindrical member, a surrounding stationary sleeve member in which said cylindrical member is journaled in substantial gas tight relationship, both members being provided with channels therethrough for gas to be sampled, said channels having orifices at the outside of the inner member and at the inside of the surrounding member to communicate periodically when the inner member is rotated, and means including at least one bimetallic plate to support one of the members, said plate being bent in dependence on its temperature to displace the supported member in relation to the other member to compensate variations of the volume of the gas by changing the passage area between the channels.

3. A sampling device for continuous supply of a constant amount of gas per unit of time, comprising a cylindrical member, a surrounding stationary sleeve member in which said cylindrical member is journaled in substantial gas tight relationship, a drivingshaft for rotating the inner member, a slidable connection between the shaft and said inner member to permit the latter to be displaced in axial direct-ion, both members being provided with channels therethrough for gas to be sampled, said channels having orifices at the outside of the inner member and at the inside or said surrounding member to corn-- municate periodically when the inner member is rotated, and means including at least one bimetallic plate to support the inner member, said plate being bent in dependence on its temperature to displace the rotatable member in relation to the surrounding sleeve member to compensate variations of the volume of the gas by changing the passage areabetween the channels.

4. A sampling device for continuous supply of a constant amount of gas per unit of time, comprising a cylindrical member, a surrounding stationary sleeve member in which said cylindrical member is j'ournaled in substantial gas tight relationship both members being provided with channels therethrough for gas' to be sampled, said channels having orifices at the outside of the inner member and at the inside of said surrounding member to communicate periodically when the inner member is rotated, manually operated means for displacing one of the members in axial direction to adjust the passage area between the channels, and means including at least one bimetallic plate to support one of the members, said piate being bent in dependence on its temperature to displace the supported member in axial direction in relation to the other to compensate variations of the volume of the gas by changing the passage area between the channels.

References Cited in the file of this patent UNITED STATES PATENTS 857,463 a June 18, 1907 2,333,934 Jacobson Nov. 9, 194-3 2,647,402 Ibbott Aug. 4, 1953 

1. A SAMPLING DEVICE FOR CONTINUOUS SUPPLY OF A CONSTANT AMOUT OF GAS PER UNIT OF TIME, COMPRISING TWO MEMBERS HAVING SURFACES CONTACTING EACH OTHER, MEANS FOR ROTATING ONE OF SAID MEMBERS IN RELATION TO THE OTHER, BOTH MEMBERS BEING PROVIDED WITH CHANNELS THERETHROUGH FOR GAS TO BE SAMPLED, SAID CHANNELS HAVING ORIFICES IN SAID CONTACTING SURFACES TO COMMUNICATE PERIODIALLY WHEN THE ROTATABLE MEMBER IS ROTATED, AND MEANS INCLUDING AT LEAST ONE BIMETALLIC PLATE TO SUPPORT ONE OF THE MEMBERS, SAID PLATE BEING BENT IN DEPENDENCE ON ITS TEMPERATURE TO DISPLACE THE SUPPORTED MEMBER IN RELATION TO THE OTHER MEMBER TO COMPENSATE VARIATIONS OF THE VOLUME OF THE GAS BY CHANGING THE PASSAGE AREA BETWEEN THE CHANNELS. 